New Scientist - USA (2019-12-21)

62 | New Scientist | 21/28 December 2019

L

IVER feeling torpid? Nerves debilitated?

Stomach weak? Do as the Victorians

did and pour yourself a drop of the soft

stuff: a tongue-tingling glass of tonic water.

Best known today as one half of the ultimate

English cocktail, it started out as a drink to

revitalise the body and revive the spirits.

Now, its sparkling story has been revealed,

thanks to two tonic-tippling botanists.

On a blistering August afternoon – very

definitely a gin-and-tonic sort of day – I headed

to the Royal Botanic Gardens, Kew to

meet Kim Walker and Mark Nesbitt. I soon

found myself in the blissfully cool interior

of a temperature-controlled storehouse.

There, among Kew Gardens’ vast assemblage

of botanical treasures, is the world’s largest

collection of bark from cinchona trees,

the source of tonic’s most vital ingredient:

quinine. Rack after rack of floor-to-ceiling

shelves hold a thousand bundles of bark

along with bottles, packets and jars of

cinchona seeds, powders and extracts.

Walker and Nesbitt have scoured this

collection and Kew’s archives to trace the

evolution of tonic water for their new book,

Just the Tonic: A natural history of tonic water.

Both the taste and the fizz, it turns out, are

rooted in medicine. It is a tale of discovery,

adventure, imperial ambition and biopiracy,

with a generous garnish of myth.

Cinchona trees are native to South America.

There are 25 species (the 25th discovered

only in 2013), all restricted to cloud forests

strung along the eastern slopes of the Andes

from Colombia to Chile. The trees’ bark

contains dozens of bitter alkaloids, including

quinine. In nature, quinine’s job is to deter

hungry herbivores. In tonic, it provides the

characteristic bitter flavour and refreshing

astringency. But for almost 300 years, it was

the only cure for malaria known in the West.

As befits a “miracle cure”, much of its story

is unreliable. How, for instance, were the bark’s

Gin’s other half has a sparkling history,

finds Stephanie Pain

The bark of cinchona trees,

native to Andean forests,

yields quinine for tonic water

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